Ergonomics - edited study book -


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ergonomics,human factors, psychology, engineering, industrial design,visual ergonomics, cognitive ergonomics, usability, human–computer interaction, physical ergonomics

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Ergonomics - edited study book -

  1. 1. Hungary-Croatia IPA Cross-border Cooperation Project "Health and Work Project" Balazs Pankasz Ergonomics edited study book 1
  2. 2. Introduction Ergonomics is a concept that Western-Europe has long been familiar with. Lately it isbecoming widely known in Hungary too, it appears in the media, and it is becoming part ofadvertisements and product manuals. If something is said to be ergonomic that has a positiveconnotation, even though we rarely know what the expression really means. The labelergonomic is to be found on various products and it means a definite benefit in thecompetition. At the same time though such concepts as design, usability, user-friendly andergonomics get mixed up in people’s minds. This is also why this study fills a gap, as it showsin five chapters what ergonomics deals with, what ergonomic design means, and what asuccessful product is from an ergonomic point of view. The different chapters deal withcurrent trends and phases of ergonomics, such as the designing of computer hardware andsoftware, or the fulfilling of the special strata’s – e.g. physically challanged, pregnant women,children – needs. The chapter on office ergonomics is an example of complex ergonomicsolutions, as it takes many aspects into consideration (aspects like the designing ofworkstations, the importance of how things are arranged in a given space, the noise, the badclimate, or the bad lighting). So this study might be filling some gap, but it has had antecedents. In Workpsychology, edited by Sándor Klein and published in 2004, there is a separate chapter onergonomics by Miklós Antalovits. This chapter describes the basic concepts and main phasesof ergonomics, and even shows through an example what the ergonomic aspects are whendesigning a product. So the goal of this study is to continue the work that Sándor Klein hasbegun, with the help and presentation of new approaches and the latest foreign literature ofthe field. As for the structure of this study, it can be divided into five larger sections. In thetheoretical introduction the main phases of ergonomics will be described, together with thedominant issues of each phase. In the first phase of ergonomics the main interest ofresearchers was the senso-motoric level of the human-machine interface: their concern washow to design the screens and operating-boards of machines so that it meets our knowledgeabout human movement and perception. The next phase was defined by systems theory,which inspired various different sciences: surpassing the human-machine interface, experts ofergonomics started to observe the whole system of human-machine and surroundings. In thethird phase ergonomics becomes a benefit in the competition on the consumer market ofproducts. What is ergonomic sells well, so ergonomic design becomes a priority for 2
  3. 3. enterprises in the 1970s. In the 1980s cognitive ergonomics redefines classical ergonomics. Itis still about the human-machine interface, but the now more complicated machines raise thefollowing problem: how to fit human and artificial intelligence together? From the 1990sproduct ergonomics is still a leading branch of ergonomics, aspects of safety become moreimportant, new methods appear on the scene (for example the involvement of futureconsumers in the process of designing), and the designing for those with special needs gainsmore ground. Looking at the chronological evolution of ergonomics it becomes clear thatergonomics is a new science, the focus, goals and methods of which are constantly changingand developing. The recognition of ergonomics has changed significantly, although thespreading of concept does not necessarily coincide with the exact interpretation of theconcept. The part on the methods and the criteria of a good product shows the complexity ofthe fitting of human, machine and system in which not only human factors play a great role,but other, e.g. engineering or economic aspects as well. In the second chapter of the study the problem of the human-machine interface is dealtwith in detail. On the one hand it refers to the classical ergonomic problem about “handlesand scales”. How to construct the operating-boards of machines and instruments operated bypeople? In this same chapter another issue is dealt with at the same time: that of a new level ofinterface: the encounter of human and artificial intelligence. The central issue of the fieldcalled cognitive (and software-) ergonomics is how to fit the higher human thinking (such asdecision-making, judgement passing, creativity) and the artificial intelligence to each other.Obviously the experts mainly examine the communication between human and machine inrelation to computer softwares. With the spreading of personal computers ergonomics hasentered a new phase in terms of methodology as well, as the involvement of the users at anearly stage of the designing, the so-called ’from the bottom up’ projects are more widespreadnow. In the third chapter the field where the common man mostly encounters ergonomicswill be dealt with: that is the people-centered designing of everyday, either in- or out- of workobjects. Nowadays, if a product can be called ergonomic, it raises its value directly while it isnot clear what is considered good ergonomic designing. Is it the user-friendly nature ofsomething, or the usability? The”good” shape or the function? In the third chapter first thecycles of the product-designing will be introduced, then those aspects that make a productgood from the point of view of human-product fitting. Here two independent, but very closelyrelated approaches will be discussed: on the one hand the concept of usability drawn up bySchakel (1981) which is often referred to with the acronym LEAF (Learning, Efficiency, 3
  4. 4. Affection and Flexibility). The other approach is associated with the name of Antalovits(1998) who defines the ergonomically good product on the basis of three criteria: efficiency,safety, comfort. The next part of the chapter is set out to find the answer to the question whichdesigning strategies lead to usable, well-fitted products. It is important to emphasise thatdesigning strategies can be put in an order on the basis of the probability of their leading to anergonomically good output, but the choosing or dismissing of a strategy depends on more thanone factors. For example the ergonomically good strategy is not always satisfactory from aneconomic point of view, and the experts of development always have to look for compromisesamong the factors. At the end of the chapter the issue of software-ergonomics will be dealtwith: what makes the using of a software easy for a user? In the fourth chapter the advantages of the approach that takes human factors intoconsideration will be described through a practical example. Office ergonomics uses theresults of various ergonomical researches. In the process of designing an office surroundings,such factors should be taken into consideration as environmental effects (as noise, lighting,climate, temperature), or issues arising from the nature of the work done (for example becauseof the long-term sitting the adequate design of chairs and tables is important, and the usage ofcomputer raises many questions like the exhaustion of the eyes, the possible damage of wristsand hands). The design of the office surroundings is in close relation with the preservation ofthe employee’s health: the injuries and illnesses of intellectual occupants are related to staticwork to a great percentage, the constant usage of the mouse and the keyboard, the staring atthe monitor for a long time that is, to things that ergonomic designing can reduce a greatamount, or even eliminate. The fifth and at the same time the last chapter of this book sets out to find the answerto how ergonomics tries to meet the needs of “special” consumers. The term “special” inrelation to ergonomics can refer to many different aspects: maybe it is just applied forconsumers who are too short, too tall, too thin or overweight, or their dominant hand is theleft one. Pregnant women, elderly people and physically challenged people are alsoconsumers with special needs. The challenge of ergonomics here is that the basic humaninformation that ergonomics uses during the process of designing is different in their case.The products, instruments and work surroundings have to be designed in a way that the fittingof human, machine and surroundings could be realized in the case of these consumers withspecial needs too, while aspects of efficiency still should have a priority. Even in the case ofsuch an everyday product as a bath it is evident that elderly people have to face different 4
  5. 5. problems than average consumers while using the product: getting in and out, temperatureregulation is a different challenge for them than for the younger ones (Nayak, 1995). Hopefully this review reaches its goal: the concept of ergonomics and issues ofthe field observed give an elaborate introduction for the reader who encounters the subject forthe first time. 5
  6. 6. Chapter One: The Concepts, Phases and Methodology of Ergonomics. What is GoodDesigning Like? Has it ever happened to you that you could not heat your coffee in a microwave oven?In the picturesque anecdote of Normann (1988) this is what happened to Kenneth Olsen, Mscin engineering, president of Digital Equipment Corporation (DEC) with the oven made by hisown company. Or that you turned on the wrong hot plate as it was not evident for you whichswitch belonged to which hot plate? Perhaps that after hours of typing your wrist hurtbecause of using the mouse, your back ached because of the uncomfortable chair, while youwere sick and dizzy because of the exhaustion of your eye-moving muscles? Are you familiarwith the unpleasant feeling when an object, a instrument is too small, too big, has too manyor not enough programs, or when it is impossible to tell what the purpose of certain softwaresis? It is too often experienced that the objects surrounding us are like the Procrustean 1 bedthat we just cannot fit into. The science of ergonomics is set out to find the answer to how abetter fitting of the person, the objects and instruments used by him and the (work)-surrounding could be reached. The emphasis being on the setting and the securing of theharmony between the person and the technical surrounding (Antalovits, 1998). The term ergonomics comes from the combination of two Greek words: ergos meanswork, and nomos means laws. The expression is generally attached to the name of professorK. F. H. Murrel (1965), who was one of the scientists who gathered together in room 1101 inHotel Queen Anne in London on July 8th, 1949 with the purpose of founding a team that dealtwith the human performance (”Human Performance Group”) (Pheasant, 2003) 2. Thesescientists came from very different fields of science: there had been an engineer, apsychologist, a physiologist, a doctor and even an industrial safety specialist. During theSecond World War, which had only just ended recently, they all had been involved inresearches about the efficiency of the fighting man, and they all had realised the complexrelationship between human and machine. They had founded the Ergonomics ResearchSociety before the end of 1949, which later changed its name to Ergonomics Society. In the1 Procrustes is from the Greek mythology. He was a notorious thief, who laid his victims in his bed and torturedthem: if his victim was of high stature, too long for the bed, then he cut them shorter; if the victim was too short,he stretched them until they reached the two ends of the bed. The “Procrustean bed” is a well-used term inergonomics and it refers to solutions that most actual consumers could only be forced into.2 It is important to note though that the phrase was first used in a Polish newspaper in 1857. But apparentlyMurrel did not know about this first usage of the word and he suggested the adaptation of the term ergonomics asa name for the new branch of science independently (Harvey, 2004). 6
  7. 7. chapter about the history of ergonomics we will see that the issues in ergonomics have a longlist of antecedents, nevertheless it is safe to say that ergonomics was born in the SecondWorld War. During the war the American Air Force had lost more than 400 airplanes becauseof errors that originated in the misplanning of the ”meeting” of human and machine(Antalovits, 1998). The management of the army and the designers of the machines had noother choice but to face the fact that even though the machines were technically improved,they knew more, the whole system became less reliable. The problems were the results ofignoring the people who managed the machines during the process of the designing of themachines, and the basic laws regarding the human perception, detection, way of acting andway of processing information. The damages caused by the war were dramatic indicators ofan earlier just perceived truth: the machines and the work surrounding have to fit the humanconsumer. In the absence of optimal fitting there are various consequences: the performancelessens, user frustration escalates, the probability of accidents escalates, and there is physicaland mental health damage is to be expected (Pulat, 1992). This is the first examined issue ofergonomics: the encounter of human and machine on the level of perception-motion. What thedisplay or user interface of a machine should be like, which operations are natural and whichare unnatural for people? How to meet human needs and improve efficiency of the machinesat the same time? As these questions suggest, ergonomics is a practical science the goal ofwhich is to “scientifically observe the interaction between human and his work surroundings”(Murrell, 1965). The task of ergonomics is to collect the basic information about peoplenecessary for planning, as well as to provide an independent methodology for this process. Inorder to be able to observe people we often opt for the analogy of the information processingsystem which in the case of human beings consists of inputs, intermediate processes andoutputs. Inputs are the stimuli coming from our surroundings which we either react to orignore. Between perception and procession on a higher level there is cognition and attention.What happens on a higher level is often simply referred to as “thinking”. This involves suchprocesses as decision making, problem-solving and creativity. All these human cognitiveprocesses are permeated by memory, short term work-memory as well as long-term memory.At the end of the process there usually is some motoric reaction, action. Like any othermodels, this is also a significant simplification 3 but it helps to illustrate what types ofinformation should be taken into consideration when designing for humans 4 (Noyes, Garlandand Bruneau, 2004). The model shows that the characteristics of perception, cognition,3 Ignores important, interaction-modifying human factors such as emotions.4 This is also called “human-centered design” (Harvey, 2004). 7
  8. 8. attention, “thinking”, memory and motoric relations are primarily interesting for researchersof ergonomics. Afterwards the specialists who put ergonomics into practice – primarilyengineers – will try to design machines and systems adapted to human features based on thisbasic information5. As it has already been mentioned, the first issue of ergonomics was the adequateplanning of the encounter of human and machine, the human-machine interface, on a sensory-motoric level. During the practical appliance of the new science though it became clear thatthere are several other issues that the experts of ergonomics could contribute to in merits.Besides, quite a few “ergonomic” issues only arose after the birth of this branch of science.The chronological evolution of ergonomics will be followed through in the first part of theintroductory chapter, beginning with the antecedents of ergonomics and finally arriving attoday’s trends. The periodization does not mean though that a given issue had only beeninteresting to the scientists in the given period; simply these issues arose in this order. Forexample ergonomics specialists still seek for solutions of the human-machine interface on asensory-motoric level. This is well-indicated by the researches on different ergonomicalkeyboards and mouses. The following figure about chronology shows what periodsergonomics has gone through (Fig. 1.). Figure 1.: Periods of Ergonomics (after Antalovits, 1998)5 It is worth noting that according to Antalovits (1998) only those solutions are ergonomical where one part ofthe specialists involved come from fields dealing with the human being (e.g. psychology, biology, medicalsciences), and the other part of them has Ms in engineering. 8
  9. 9. Antecedents of Ergonomics: Industrialization, Work-Organization by Taylor The roots of ergonomics date back to the beginning of the century, the era ofindustrialization, the era of large-scale technologies (Antalovits, 1998). Primarily thescientific management movement created by Frederick Taylor is worth mentioning, theprimary goal of which was to rationalize work6 (Taylor, 1911). He did this with the help ofsuch methods as movement- and time analysis. Although there had been some forwardpointing discoveries (e.g. Frank and Lilian Gilbreth’s researches on sergeants In: Antalovits,1998), the ergonomic approach was alien to current notions. In Taylor’s thinking, forexample, the relationship among machines, instruments and men played a significant role, buthere the idea was to find the right person for the right job, or that it is the person that shouldbe adjusted to the machine. Dekker (2004) points out the differences well in the light ofhuman errors between pre-ergonomics- and ergonomic thinking. Human errors had been seenas the reasons for the collapse of systems before ergonomics appeared on the scene. Peoplewere seen by engineers as the only unstable points of a system: the instruments, machines andsystem in reality would work safely if it was not for the unpredictable human thinking. Theergonomic approach sees human errors not as reasons, but as symptoms that indicate a deepererror somewhere in the system. The error here is a planning error: simply during the processof planning the peculiarities of the people who operate the machines had not been evaluatedcorrectly, or had not been evaluated at all. Figure 2.: Classical and Ergonomic Approach of Human Errors One important reason for the change in the approach is shown by Noyes (2004). Inmost of the factories in the 19th and in the first part of the 20th century humans were the“sacrificable” elements of a system. The human workforce was not particularly valuable asmost of the jobs did not require any special qualifications. If somebody dropped out of work –6 This movement became known as taylorism. 9
  10. 10. either because they got hurt or because they died – they were easily replaceable. The workerhired to his place learned the mostly manual work quickly. It is easy to see then that beforethe Second World War, save for a few sporadic exceptions, there had not been an ergonomicapproach, though the appearance of one is not even justified yet 7. The situation changed in theSecond World War when it turned out that handling of the advanced technologies (e.g. radarscreen, operators and displays of instrument panels of airplanes) was a challenge for theoperators. Many of the operators found it hard to learn the application of new technologiesand especially at the early stages of the learning process made mistakes, often with graveconsequences. It is possible that at a time of peace this would not have mattered so much, butduring the war educated workforce was increasingly appreciated: while there was no time forelonged trainings, the lack of trainings claimed financial and human sacrifices. Theexperiences gained during the Second World War made it clear that the needs and the abilitiesof human operators (e.g. pilots, navigators) could not be ignored in the process of planningthe new technologies. This realization gave birth to the first, “classical” phase of ergonomics,which is also referred to as the ergonomics of “handles and scales” (Antalovits, 1998). Thisphase will be described in the next section. The Birth of Ergonomics (1945-1960): Human-Machine Interface on the Sensory-motoric Level As it has been mentioned before,3the Second World War showed the challenges both the time and Figure 3. Altimeter with indicators. Grether (1949) demonstrated that the accurcy of its reading was a problem for the pilot.7 During the First World War there already had been a shift from the early industrial approach that ignoredhuman factors towards an ergonomic approach. It is Oborne (1982) who draws the attention to the fact that in thecartridge factories women could not operate the machines traditionally designed for men so efficiently.Engineers realized though that the problem was not with the women, but with the designing of the machines. 10
  11. 11. dramatically in relation with the design of the human-machine interface (where humanwas in close contact with the machines) (Grudin, 2008). During their application manysolutions turned out to be far from the optimal. Grether’s observation (1949) demonstrated forexample that the traditional altimeter with three indicators which were used on war-planestoo, not only distracts the pilot’s attention for too long – it took more than 7 seconds just toread it –, but in 12% of the readings the pilot was more than 300 metres out when defining hisaltitude. Grether (1949) proved that a different design lessened the time spent on reading thealtimeter while the accuracy of the reading improved. The difference between the traditionaland the different design was that while the first ignored the “human factors” the second tookthat into consideration. A little detour is necessary because of the term “human factors”: this name becamewidespread after the Second World War in the United States of America. Its researchers andpractical experts dealt with similar issues as the specialists of ergonomics in Europe, althoughthere were slight differences between the two approaches. The scientific background of theexperts dealing with human factors in The States was less diverse than in Europe. The teamengaged in human factors had been formed inside the American Psychological Society in1957 and it was only later that it became an independent society called “Human FactorsSociety”. The European school, as we have already seen, was much more marked bydiversity, as already in the first meeting in 1949 next to the psychologists biologists,physiologists, doctors and engineers were represented. From now on though the termsergonomics and human factors will be handled as synonyms, which coincides with thepractice of recently published specialized books (Antalovits, 1998). This change is alsoreflected in the fact that the Human Factors Society founded in The States has recently alteredits named, and now it is called Human Factors and Ergonomics Society (Stanton, 2003). It is evident from the chronology that experiences of the Second World War startedboth in the United States of America and in Europe those researches, research laboratoriesthat sought to solve the issue of the human-machine interface. Logically the army played hostto the first research laboratories: in The States the Ministry of Defense started theMANPRINT8 program which wanted to solve the issue of the human-machine integration. Itwas not long after that the Ministry of Defense in the United Kingdom announced a similarprogram (Harvey, 2004). In the meantime the Ergonomic Research Society was formed in1949 in the UK, then in 1957 the first ergonomic periodical, the Ergonomics was issued too.8 MANpower and PeRsonnel INTegration. 11
  12. 12. In 1959 the “International Ergonomics Association” was established, which held its firstconference in 1961 in Stockholm (Antalovits, 1998). What was essential then was therecognition that the not optimal – suboptimal – operation of certain war instruments derivedfrom the ill-fitting of human and machine. The consequences of this ill-fitting weresubstantial for the army: there was either a need for elonged and expensive training for theapplication of the instruments, or in the lack of these the weapon-systems could not reachtheir planned parameters (Harvey, 2004). On the sensory-motoric level of the human-machineinterface researchers and practice-specialists have to consider two problems: in what formshould the machine give signs, share information with the operator (screen), and whatoperating-board should it have (control). The ergonomic connections that have been exploredin this field will be discussed in detailed in chapter two, the subject matter of which is thesensory-motoric and the cognitive fitting of the human machine interface. System ergonomics (from the 1960s): Examination of Human-Machine-Surroundingsas a System Throughout the 1950s the development of ergonomics was steady thanks to themilitary preparations of the cold war and the space research contest. It was in this tome thatgeneral systems theory was born (see e.g. Bertalanffy, 1950), which had a fertilizing affect onmany fields of studies, ergonomics among them. Ergonomics got away from the problem ofthe human-machine sensory-motoric interface and began to think on a level of systems aboutthe relationship of human, machine and surroundings. It was also during this time that bigcompanies recognized ergonomics’ – mainly economic – potentials, which gave a head starton ergonomics’ military technology-, and space research-free development 9. Throughout the1960s human factors were utilized not only in the designing of machines and technicalinstruments, but they also played a great part in the designing of surroundings andoptimalization of production systems (Antalovits, 1998). Product ergonomics (from the 1970s): The Ergonomics of the Designing of Products Product ergonomics is practically the joint segment of industrial design andergonomics (Antalovits, 1998). In the 1960s big companies recognized the direct economic9 Although it still stands that the discoveries of ergonomics almost always appeared first in high-technology (e.g.Military technology, space research) (Antalovits, 1998). 12
  13. 13. advantage of ergonomics after the revelation that it is not only the optimal design of machines and instruments, but also of the whole work surroundings that has an effect on the performance of people and so this also effects the efficiency of the company. In the 1970s ergonomics’ usefulness and itsability to directly produce profit became even more evident for the companies. Amid theintensifying competition of the car industry, consumer electronics and companies producingconsumer products it was discovered soon enough that most operators of a market can offerthe same quality for the same price. Consumers chose from the many similar products basedhow much those met their individual needs. The assertion of the ergonomic aspects of aproduct throughout its whole life cycle (starting from the raising of the idea, throughout itsrealization and its introduction to the market, until the recyclebility) had a significant effect onhow well the product sold. According to Noyes (2004) the sooner human factors are takeninto consideration while designing, the ”better” the product will be from the ergonomic pointof view (it will be discussed at the end of the chapter what makes a product or design “good”).Different aspect of product ergonomics will be discussed in detail in the third chapter of thisstudy. Cognitive- and Software-Ergonomics (from the 1980s): Expansion ofComputerization, the Introduction of PCs. Human-Machine Interface on a Cognitive Level. In the 1980s researches on ergonomics had two significant driving forces: one of themwas the widespreading of information technology – and especially that of personal computers.The other one is connected to those major catastrophes which happened close in time at theend of the 1970s and the 1980s (in 1979 the accident in the nuclear power plant of Three MileIsland, in 1984 the disaster in the chemical plant of Bhopal, India, in 1986 the Chernobyldisaster, in 1986 the crash of the spaceship Challenger and in 1987 the accident of the ferryZeebrugge). 13
  14. 14. Figure 4: Nuclear Power Plantation of Chernobyl The invention of the silicone chip and the widespread of computers opened a newchapter in the history of ergonomics: researches on cognitive and software-ergonomics(Hendrick, 2002). This new aspect raised the importance of ergonomics in general asaccording to the estimations of Hendrick (2002) the number of ergonomic positions increasedby 25% in the 1980s, in the market sector. The widespread of personal computers drew theattention on a daily basis to the importance of designing hardware and software keepinghuman factors in mind. The encounter of human consumers and computers was nothing elsebut the reformulation of the first, classical ergonomic problem – the sensory-motoric fitting ofthe human-machine interface – on a higher level: the fitting of the human-machine interfaceon a cognitive level. This is the level that has formally been defined as “thinking” after Noyesand his co-workers (2004): mental working capacity, decision-making, communication ofhuman and computer, creativity and similar phenomena included here. The effect of the accidents and disasters were twofold: Antalovits (1998) pointed outthat over the analysis of the reasons of the catastrophes the conclusion was made that onecommon reason was discovered behind all disasters. This was the under-valuation of humanfactors – nay, their ignorance in some cases – amid the designing and operating of thesystems. Similarly to the widespread of computers the accidents helped to reinforce theposition of the study of ergonomics too as the keeping of ergonomic aspects in mind was nowpassed into law in more and more contrives, or the already existing laws were aggravated.According to Hendrick (2002) the practice of the juries of the United States of America wasclear and consistent in this field: it is the responsibility of the leaders that they payed enoughattention to the ergonomic aspects in the designing of their products as well as in the design oftheir work surroundings. In the absence of this they would have to face serious penalties. In 14
  15. 15. relation with the accidents the researchers arrived at a shocking discovery which consequentlylead to a subfield of ergonomics, macro ergonomics becoming more important: it is absolutelypresumable that the engineers – from an ergonomic point of view – do an excellent job in theprocess of designing of the parts, modules and subsystems of a given system, but they still donot reach the desirable efficiency and safety. The reason of this is that they do not pay enoughattention to the macro ergonomic designing of the whole work system 10 (Hendrick, 1984,1986a, 1986b). The analysis of the disasters (primarily in the case of the accidents in thenuclear power fields of Three Mile Island and Chernobyl, and in the case of the disaster in thechemical plant of Bhopal) many of the researchers have arrived at the same conclusionindependently from one another (Meshkati, 1986, 1991, Meshkati and Robertson, 1986,Munipov, 1990). Trends in Ergonomic Research Ergonomics is a young science which is under constant development and change asnew problem arise every day in relation with the encounter of human and machine and humanand work surroundings. The speed of changes is shown clearly by the fact that todaysoftware-ergonomics is one of the most important parts of the human factors researches, whilethe first personal computers were only sold in February 1978, and the widespread of thepersonal computer sin the workplace only went through at the beginning of the 1980s (Noyes,2004).10 This seems as if system ergonomics got more important, but according to Hendrick (2002) it is not only this,but a change in the approach as well: while system ergonomics examines the fitting of the individual and thework surroundings primarily and serves as a kind of environmental ergonomics, macro ergonomics lays stress onthe fitting of human and the whole system, work system. 15
  16. 16. Figure 5: One of the first personal computers, Xerox Alto in 1973 It is expected that in the future the previously described trends will get stronger:cognitive- and software-ergonomics, as well as the safer designing of the work surroundingsand the products too. Software-ergonomics changes, alters the methodology of ergonomicresearches, as it is different in its nature from the previous issues concerning human factors.Since in the case of softwares there is no average consumer, as personal computers are presentin almost all of our lives. During the process of programming such softwares have to becreated that meet the criteria of optimal fitting in the case of beginners as well as advancedconsumers. Another important factor to be kept in mind in the process of the designing is thatengineers and IT experts have to forget the traditional ”from the top down” design, as thesuccess of a given software is realized if the consumers is initiated as soon as possible, andparticipation is possible (Antalovits, 1998). As we learn more and more about people – thebasic information that are characteristic of people – and the operation of machines andinstruments, it is to be expected that the development of “instruments”11 will be moredifferentiated, and special- or stratum needs will be taken into consideration more. It has been mentioned before that ergonomics is a study with its own methodology,where the task of researchers is, through the collection of basic information, to contribute to11 Using the term product in the broad sense of the word. 16
  17. 17. the harmony between human and machine. The methodology of ergonomics will be describedin the next chapter. The Methodology of Ergonomics A part of the methodology of ergonomics coincides with the methods of other studiesabout human beings, while there are some special procedures worked out by ergonomicresearchers (such as the heuristic evaluation). In this part we will describe the differentmethods, how they can be grouped, all the while stressing the advantages and disadvantagesof each method. The first big dimension along which ergonomic methods can be grouped according toNoyes (2004) is the differentiation between formative and summative methods. Here whatmakes the difference is that one method can be applied in a given part of a product’s lifecycle. Formative procedures are applied in the process of the designing of a product, whilesummative procedures are more suitable for the analysis and evaluation of finished product.This difference is often shown through the following, picturesque example: “when the cheftastes the soup while making it that is formative evaluation, when the guest of the restauranttastes it that is summative evaluation”. It is important though, that most of the 25-30methods12 in the methodology of ergonomics can be applied both in the process of thedesigning of a product and after it has been introduced into the market. Another aspect is the objectivity of the methods. Subjective are the methods where themeasuring is indirect. It is the consumer who is asked to relate his/her impressions andexperiences in some form. While subjective methods are suitable for the measuring ofconsumers’ attitudes primarily, objective methods apply direct measurements and give moreobjective results. Before a more detailed description of these procedures 13, let us see in chart1. The most important subjective and objective methods14.12 According to Noyes (2004) the number of methods depends on how much we differentiate among theparticular procedures. The group of methods called task analyses for example stands for 100 more or lessdifferent procedures in reality.13 During the description of the methodology such general procedures that most human sciences apply, asquestionnaires, interviews and laboratory examinations will not be elaborated on, for there are manymethodological summaries available on these (e.g. Howitt and Cramer, 2000 book of methodology).14 For simplification in Chart 1. empirical methods (laboratory methods) are listed among objective methods,although these are often differentiated along the control dimension (Noyes, 2004). 17
  18. 18. Subjective Methods Objective MethodsHeuristic Evaluation ObservationCheck list Task analysisFocal groups Human Reliability AssessmentQuestionnaires Examinations in laboratoriesInterviewsChart 1.: Subjective and Objective Methods in Ergonomic Researches Subjective Methods Subjective methods operate with data based on indirect accounts given by consumers.Among others, the heuristic evaluation, the check list, focus groups, questionnaires andinterviews belong here. Most of the subjective methods can be categorized as “fast and dirty”(Noyes, 2004). As the term suggests, information can be collected fast through these methods,but they do not reflect on the question “why?” that would give reasons so much, and mostlythe validity and reliability of the data is questionable. Objective Methods Instead of consumers’ attitudes objective methods operate with directly measurabledata. Observation, task analysis, Human Reliability Assessment and controlled laboratoryexaminations belong here. Objective Methods 1: Observation The observation of the consumers without a doubt hold the advantage that it gives a lotof information for the experts of ergonomics that the predicting of which would have beenhard – or impossible – without the observation. The image validity of this method is verystrong, which means that it provides reliable information on what the consumers actually dowith a product, or an instrument. Noyes (2004) quotes an observation examination of acolleague, Chris Baber: Baber and his co-workers observed at a London Tube station howpeople used the ticket vending machines. It was a shock for the researchers that many peopletried to fit notes into the spot made for coins. This type of appliance is hard to detect from thedesign office, still it might be a real difficulty during the operation of the product. This iswhere the advantage of the method lies: may the utilization of a product be weird, it will befound out during the observation. The disadvantages of this method are: 18
  19. 19. • The reason of the attitude is not revealed • The control of the observer is low • Ethical issues arise • It is time-consuming and • The effect of the observation on the observed is uncertain One of the most serious problems is that although the observation shows what it is thatthe consumer does, it does not show why they do it. This can be a problem mainly duringredesigning. To stay with the Barber-problem: it was clear from the observation thatconsumers tried to put notes into the coin spots, what was not clear was what feature of thevending machine got them confused. Is it possible that it is not clearly indicated that the givenspot can only hold coins? If this is the reason behind the attitude, how should the machine bealtered? Questions like this cannot be answered with the help of the observation method. Apossible solution could be to ask the consumers after the observation why they did what theydid, but in most natural observed situations this is hardly feasible. The following problem inrelation with observation is twofold: it is difficult to follow through and evaluate events inreal time, so observation has to be recorded (usually audio- and video recordings). But therecording raises ethical questions: if the observants are not warned about the observation, is itlegal to record them? But if they are warned that might change the nature of the observedsituation, as has shown the researches between 1924 and 1932 made by Hawthrone. InHawthrone’s researches the observed workers still did a better job than their non-observedcolleagues when their work situation worsened (Noyes, 2004)15. The ethical question apart,another problem with the recorded observations is that they are very time-consuming:according to some estimations one hour of video observation would take ten hours ofprocessing to make a report useful for further analysis (Noyes, 2004). Objective Methods 2: Task Analysis Task analysis in reality is an umbrella term for various, more or less similar techniques(Noyes, 2004). According to Pheasant (2003) good designing projects almost always beginwith task analysis, so in this respect task analysis is a formative method. Task analysis in hisopinion is a formal, or mostly formal experiment for defining what will the consumer,operator actually do with the product or system. Task analysis determines the desirable result15 This is a problem with the laboratory experimental methods as well. 19
  20. 20. of the instrument- and system appliance, the physical operations the consumer will have toperform to reach that output, and processing requirements of the information relevant of thetask as well as the environmental compulsions. One of the most applied task analysistechniques is hierarchical task analysis where the task is subdivided into goals and sub goals.The result of the task analysis is often some sort of visual illustration, for example a flowchart (Noyes, 2004). One of the main advantages of the method is that by systematicallybreaking down the task it becomes clear where the consumers have problems in relation withthe instrument or system. One of the issues is that it is difficult to determine the ideal level ofthe division of the task, and that it is difficult to acquire this technique for the inexperiencedresearchers and practical experts16. Objective Methods 3: Human Reliability Assessment (HRA)17 Methods suitable for determining the reliability of humans (HRA) are special cases oftask analysis. Their goal is to identify the errors that arise during the different types ofconsuming. Generally speaking HRA focuses on measuring the consequences of the differenterrors this way contributing to their prevention, the reduction of negative outcomes and thehandling of errors. In the course of HRA analysis an event-tree, or error-tree is made. It iscommon in both methods that they show the errors, the ways of recovery from the errors, aswell as the probability of the occurrence of an error (Kirwan and Ainsworth, 1992). Objective Methods 4: Controlled Laboratory Examinations Laboratory examinations are often listed as a separate category, differentiated fromboth subjective and objective methods. They differ from the previously described objectivemethods in their degree of control: during a laboratory experiment researchers can exclude awhole series of variables, in order to arrive at casual correlations as clean as possible. As ithas been mentioned in Pheasant (2003)’s opinion a designing project that takes ergonomicaspects into consideration almost always begins with task analysis. What is essential is thatthe end of the process is the consumer’s test, which can be seen as an experimental method. Itis nothing but the testing of a prototype among controlled conditions. According to him it isimportant to select the participants well and to ensure that the test group consists of peoplethat represent the target audience of the product18. Noyes (2004) claims that usability is in the16 The problem is to decide which is the most appropriate method for a given analysis from among the variousdifferent task analyzing methods.17 Human Reliability Assessment.18 Sometimes though, as an alternative, it might be relevant to test the product on people that we know inadvance will have problems using the product. If they are able to operate the product efficiently, then the 20
  21. 21. focus of controlled examinations. This aspect will be discussed in detail at the end of theintroduction, so now we will only describe it shortly: in Shackel (1981)’s definition a productis usable if it is easy to learn, efficient, flexible, and the consumer likes it (this is thesubjective component of usability) 19. These aspects of usability are best tested in laboratories.The disadvantage of the experimental techniques is that they presume preliminary training,needs significant preparations and is fairly expensive. In many cases its everyday validity isquestionable too, as between laboratory and real situations there are relatively big differences. So far ergonomic methods have been divided into summative and formative types, aswell as subjective and objective methods. Stanton and Young (2003) enlist further aspectaccording to which methods can be grouped. These are: • In which part of the product’s life cycle could the method be applied20 o Can be applied for analyzing a concept (the first part of the designing of a product). For example: check lists, interviews, heuristic evaluation. o Can be applied for analyzing the design (when a certain written description, material already exists about the product). E.g. hierarchical task analysis, analysis of the task that makes the identification of the error possible, predictive human error analysis, and usually the analyses of the previous stage. o Can be applied for analyzing the prototype (the period before the product’s introduction to the market, when the product already exists either as a computer simulation or as a constructed prototype). E.g. observation, controlled laboratory analysis, and usually the analyses of the previous stages. o Can be applied for analyzing operations (after the product’s introduction to the market, the period of application and maintenance). E.g. field-work, and usually the analyses of the previous stages. • The time the analysis consumes21consumers considered more ideal will presumably be able to do so too (Pheasant, 2003).19 Very often the aspects of usability determined by Shackel (1981) are described by the acronym LEAF. LEAF=learnability, effectiveness, attitude of the user, flexibility.20 This aspect corresponds to the differentiation between formative and summative methods, but Stanton andYoung (1999) expounds on the usability of the different methods in the different life stages.21 Time actually consumed always depends on the subject of the analysis; however the relative need of time ofthe methods is indicated well in this disposition. Long as it may be, a check list that is faster than the interviewtechnique or an interview technique that is faster than hierarchical task analysis can be designed. 21
  22. 22. o “Not enough” time: check list, observation, questionnaire, design analysis, heuristic evaluation. o “Some time”: modelling on a key-stroke level, link analysis, check list, observation, questionnaire, method of weighted nets, design analysis, interviews, heuristic evaluation. o “A lot of time”: modelling on a key-stroke level, link analysis, check list, predictive human error analysis, observation, questionnaire, hierarchical task analysis, method of weighted nets, task analysis that ensures the determination of the error, design analysis, interviews, heuristic evaluation. • The output measured during the process of analyzing o To measure errors: task analysis that ensures the determination of the error, observation, predictive human error analysis. o To measure time: modelling on a key-stroke level, observation. o To measure usability: check list, questionnaire, hierarchical task analysis, interviews, and heuristics. o To measure appropriateness of the design of the product: link analysis, check list, predictive human error analysis, task analysis that ensures the determination of the error, design analysis, heuristic evaluation. After the introduction and grouping of the methods the question arises which methodis better than the other? The answer to this question will be searched after in the next part ofthis chapter. Which Method id Better? This is not a yes-no question as the usefulness of the methods depends highly on: • What is the reason of the measurement, evaluation? • What are the characteristics of the given product or system? • What external, restrictive factors are there? In many cases it is the third aspect that helps to decide which method to choose fromamong the 25-30 techniques available. External factors are: a. amount of time available b.amount of resources available c. the presence and skills of experts (certain analyzing methodscannot be realized without experts of ergonomics such as heuristic evaluation) and d. ethical 22
  23. 23. considerations. Our own goals influence how important it is for us to have strict control over agiven measurement, or that the measurement is reliable and valid. Often, especially in theinitial stage of a project, broader, but less resource-dependent techniques might do, as a sortof orientation (Noyes, 2004). What Makes a “Good” Product? As it was described in the first part of the introduction the main goal of ergonomics isto create the harmony between human and machine, human and work surroundings. It is animportant question how the good fitting can be measured that is what subjective, objective orempirical methods are at stake for the researchers and practicing specialists and how tochoose the most suitable method. There is only one, but not easy question left at the end of thechapter: what is considered to be a good product from an ergonomical aspect? Certainly formost readers such terms as “user-friendly” or “usability” sound familiar, neverthelessresearches often have to face the fact that these terms are difficult to operacionalize, to rendermeasurable22. Experts of ergonomics have made strenuous efforts to define the concept ofusability. Before the introduction of the results of these efforts let us review, along Noyes(2004), why it is so difficult to design for people. Noyes enlists several factors: • human adaptation • human creativity • human diversity and • the difference between human expectations and actual use. The first factor is human adaptation: most of the people can adapt rather well to bad orinadequate design, so the existence of a problem is not always discovered. This is not a goodsolution from an ergonomic point of view, as it does not realize human –centered design:instead of fitting the machines, instruments and systems to the human, it is the human that fitshimself to them. A good example is the design of today’s keyboards: the letter allocation ofthe QWERTY23 keyboard was created in the 1960s and it is still the most widespread layout tothis day despite the fact that many researchers have presented that this is not the optimal formof the allocation of the letters (Lehto and Buck, 2008). The second factor is in close relationwith the adaptation: human creativity. People are not only good at adapting themselves to bad22 This is especially true in the case of the term “user-friendly” (Noyes, 2004).23 The acronym QWERTY refers to the upper line of the letters of the keyboard. 23
  24. 24. designs, but also at creatively enhancing the adequacy of the design. On an operating boardwhere the switches are impossible to tell apart for example, the operators often put differentstickers (like beer labels, magnets, etc). This is a creative solution, but it does not cover up theomission made by designers and technicians. The variety experienced in human performanceis a challenge in the designing process: people compared to one another, and even one personcan perform very differently from time to time. This fluctuation in one person’s performanceis a real challenge for the designers. Maybe a given user during a test will perform lower withan ergonomically better designed product than he would with a less well designed product at adifferent time. Because of this during the data processing instead of the actual performancenow what is becoming generally used is the so-called reliability interval, which estimates thatbased on the observed performance what performance would a given person give in 95 casesout of 100. The fourth question has to do with human expectations: if a consumer was askedthe question, which washing machine would they choose, they would probably mention manyprograms on the washing machine as an advantage. Reflecting on this, designers have createdwashing machines that can operate with up to 20 programs. In reality though most of theconsumers only use two programs – a quick and a slow wash program. What consumers saythey would like to use is very often different from what they actually do. Pheasant (2003), citing one of the pamphlets of the Ergonomic Society, defines theergonomically well designed product as the following: Try to use it! Think about all the ways and circumstances in which you will want touse it in. Does it match your body proportions, or could it fit you better? Can you see or heareverything that you should see and hear? Is it hard to make an error during its use, or is iteasy? Is it comfortable to use it? Is it comfortable starting to use it? Could it be improved? Isit easy to learn how to use it? Are the instructions unambiguous? Is it easy to clean it and tomaintain it? If your answer was ”yes” to all of these questions then during the process of thedesign You, the user had probably been taken into consideration as well. The text of the pamphlet highlights what criteria the product has to meet in order torealize the harmonic fitting of human and technology. Researchers of ergonomics try to drawup these aspects as observable criteria. These criteria are often referred to as usability as awhole. This term is often related to the name of Professor Brian Shackel (1981) who, rightafter the appearance and the widespread of personal computers, tried to operacionalizeusability. This is how the acronym, LEAF was born: the product should be easily learned(“learnability”), be used effectively (“effectiveness”), should meet the consumer’s subjective 24
  25. 25. evaluation (“attitude of the user”), and should be flexible during its application (“flexibility”).In the last decades these original criteria were completed by several others. Lehto and Buck,in their book published in 2008, summarized the aspects of good designing as follows: • consumption should be fast • consumption should be accurate • consumption should be safe, not endangering the consumer’s health • consumption should be easy, smooth • consumption should be easily learned • the consumer should be satisfied during the consumption (Lehto and Buck, 2008) The original LEAF criteria are clearly present in these criteria as well. It is importantto underline that the nature of the criteria shows that although during the process of designingthe goal is to make a product that meets the all of the consumer’s needs – so the designingshould be absolutely human-centered – this ideal state can never be reached in reality. Thereare more reasons for this, here two will be presented: • contradictions among the criteria • beyond the ergonomic aspect other factors, like economical, engineering, practical considerations. Contradictions among the criteria are represented by the well-known “speed-punctuality” trade – tradeoff – phenomenon. The time needed to reach the goal – speed – isoften an important aspect, but not in cases where other criteria are not met. In other words itdoes not matter how fast we get somewhere if we are going to the wrong place. Giving moretime to carry out the task often leads to more accurate outputs (for example the error rate islower). A complicating factor is that the “speed-punctuality” tradeoff is not rue for everyonein every case. Gigerenzer (2007) points out the phenomenon that in the case of experts (e.g.professional sportsmen) more time leads to lower performance: in most cases experts, thanksto their experiences, first think of the best solution. In this scenario more time leads to wrongsolutions (for example when a sportsman hesitates then makes the wrong decision). However,according to Gigerenzer (2007) in the case of beginners more time leads to more accuratesolutions. Actually the criteria of speed and punctuality work against each other: the faster thesolution, the less accurate it will be. According to Lehto and Buck (2008) it is also true that inthe relation between speed and punctuality there is an optimal range: it is true that too fast 25
  26. 26. speed leads to inaccuracy, but it is also true that too slow speed does the same (a very gooddemonstration of this is if someone tried to walk slower than normal walking speed). Another important thing is that ergonomic companies and experts of ergonomicsconstantly have to make compromises among ergonomic, economic, engineering-practicalaspects. It was Rose and co (1992) who put this into words: “in order to reach greater successwith the introduction of a new, ergonomically better method, product, it is important for thenew method, product to have economical advantages”. Lehto and Buck (2008) believe hat theminimum expectancy is that the economical value of the method, product created along thenew project should bring back the money invested in the project.Works CitedAntalovits, Miklós (1998) Bevezetés az ergonómiába. In Klein Sándor (szerk)Munkapszichológia. 2. átdolgozott kiadás, SHL Kiadó, 699-744. o.Bertalanffy, L.V. (1950) An Outline of General System Theory. British Journal for thePhilosophy of Science, 1 (2): 134-165.Dekker, S. (2004) To engineer is to err. In Sandom, C.,& Harvey, R.S. (eds) Human Factorsfor Engineers. London: The Institution of Engineering and Technology.Gigerenzer, G. (2007) Gut feelings: the intelligence of the unconscious. London: PenguinBooks.Grether, W.F. (1949) The design of long-scale indicators for speed and accuracy ofquantitative reading. Journal of Applied Psychology, 33: 363-372.Grudin, J. (2008) A moving target: the evolution of human-computer interaction. In Sears,A.,& Jacko, J. (eds) Handbook of Human-Computer Interaction. Boca Raton, Florida: CRCPress.Harvey, R.S. (2004) Human factors and cost benefits. In Sandom, C.,& Harvey, R.S. (eds)Human Factors for Engineers. London: The Institution of Engineering and Technology. 26
  27. 27. Hendrick, H.W. (1984) Wagging the tail with the dog: Organizational design considerationsin ergonomics. In Proceedings of the Human Factors Society 28th Annual Meeting (pp.899-903). Santa Monica, CA: Human Factors Society.Hendrick, H.W. (1986a) Macroergonomics: a conceptual model for integrating human factorswith organizational design. In Brown, O.,& Hendrick, H.W. (eds) Human factors inorganizational design and Management, 467-478. Amsterdam: North-Holland.Hendrick, H.W. (1986b) Macroergonomics: A concept whose time has come. In HumanFactors Society Bulletin, 30 (2): 1-3.Hendrick, H.W. (2002) An Overview of Macroergonomics. In Hendrick, H.W.,& Kleiner,B.M. (eds) Macroergonomics. Theory, Methods, and Applications. New Jersey, London:Lawrence Erlbaum Associates.Howitt, D.,& Cramer, D. (2000) First step in research and statistics: a practical workbookfor psychology students. London: Routledge.Kirwan, B.,& Ainsworth, L.K. (eds) (1992) A guide to task analysis. London:Taylor&Francis.Lehto, M.R.,& Buck, J.R. (2008) Introduction to Human Factors and Ergonomics forEngineers. New York, London: Lawrence Erlbaum Associates.Meshkati, N. (1986) Major human factors consideration in technology transfer to industriallydeveloping countries: an analysis and proposed model. In Brown, O.,& Hendrick, H.W. (eds)Human Factors in Organizational Design and Management II. 351-363. Amsterdam: North-Holland.Meshkati, N. (1991) Human factors in large-scale technological system’s accidents: ThreeMile Island, Bhopan and Chernobyl. Industrial Crisis Quarterly, 5: 133-154.Meshkati, N.,& Robertson, M.M. (1986) The effects of human factors on the success oftechnology transfer projects to industrially developing countries: a review of representative 27
  28. 28. case studies. In Brown, O.,& Hendrick, H.W. (eds) Human Factors in OrganizationalDesign and Management II. 343-350. Amsterdam: North-Holland.Munipov, V. (1990) Human engineering analysis of the Chernobyl accident. In Kumashiro,M.,& Megaw, E.D. (eds) Toward human work: solutions and problems in occupationalhealth and safety, 380-386. London: Taylor&Francis.Murrell, K.M. (1965) Ergonomics. London: Chapman and Hall.Nayak, U.S.L. (1995) Elders-led design. Ergonomics in Design, 1: 8-13.Norman, D.A. (1988) The psychology of everyday things. New York: Basic Books.Noyes, J., Garland, K.,& Bruneau, D. (2004) Humans: skills, capabilities, and limitations. InSandom, C.,& Harvey, R.S. (eds) Human Factors for Engineers. London: The Institution ofEngineering and Technology.Noyes, J. (2004) The human factors instrumentkit. In In Sandom, C.,& Harvey, R.S. (eds)Human Factors for Engineers. London: The Institution of Engineering and Technology.Oborne, D.J. (1982) Ergonomics at Work. Chichester: Wiley.Pheasant, S. (2003) Bodyspace. Anthropometry, Ergonomics and the Design of Work.London: Taylor&Francis, 2nd edition.Pulat, B.M. (1992) Fundamentals of Industrial Ergonomics. Prentice-Hall, Inc.Rose, L., Ericson, M., Glimskär, B., Nordgren,B.,& Örtengren, R. (1992) Ergo-Index. Amodel to determine pause needs after fatigue and pain reactions during work. In Kumar, S.(ed) Advances in Industrial Ergonomics and Safety 4 (Proceedings of Annual IndustrialErgonomics and Safety Conference, 1992, Denver, Colorado, USA, June 10-14, 1992).London: Taylor&Francis. 28
  29. 29. Shackel, B. (1981) The concept of usability. Proceedings of IBM Software and InformationUsability Symposium, September 15-18: 1-30. Poughkeepsie, New York: IBM Corporation.Stanton, N.A. (2003) Product design with people in mind. In Stanton, N.A. (ed) HumanFactors in Consumer Products. New York, London: Taylor&Francis.Stanton, N.A.,& Young, M.S. (2003) A Guide to Methodology in Ergonomics. Designing forHuman Use. New York, London: Taylor&Francis.Taylor, F.W. (1911) Principles of scientific management. New York: Harper. 29
  30. 30. CHAPTER TWO: The Encounter of Human and Machine. The Human-Machine InterfaceProblem on a Sensory-motoric and Cognitive Level. Two cars – “A” and “B” – following each other are speeding. A little farther ahead thepolice measures speed. Car “A” passes by the police without slowing down, car “B” reducesits speed to the speed limit. What happened to car “A” and car “B”? It is easier to tell in thecase of car “B”: most probably they noticed the police, looked at the mileometer, then withthe help of the brake pedal corrected its speed. The driver of car “B” then reeived informationfrom one of the car’s – machine’s – display, then accordingly with one of the controllers – thebrake pedal – terminated the difference between the desirable and the actual conditions. Afterthis operation the mileometer now shows the new, altered condition: gives feedback of thesuccess of the operation. If feedback indicates that the operation was not successful – forexample the car is still going over the speed limit – then the cycle starts again: the consumerreacts to the information then compares the state reached after the reaction to his originalgoal. What happened to car “A”? Here more solutions might be correct, let us examine someof them: • Wrong or insufficient information from the machine: the display sent the wrong information to the driver of the car. For example the milometer always displays the same, so the driver could not tell how fast the car goes. • The display is not, or hardly visible: the position makes it very difficult or impossible for the driver to read it. The average user’s choice would be to avoid the problem. • Incorrect feedback: another possibility is that the speed changes on the milometer, but it is not in accordance with reality. The driver stops the correction because as far as he knows he is going with the right speed. The result is the same as in the previous two cases: the driver cannot determine how fast to car is going. • Malfunctioning controllers: this is a serious functional disorder. The machine sends the correct information to the driver, the driver tries to correct, but either the accelerator or the brake pedal does not respond. The accelerator gets stuck or the pressing of the brake pedal does not slow the car down. The driver of the car receives the correct information but the car does not respond to his actions. 30
  31. 31. • The driver ignores the information received from the machine : the display sends the correct information, the controllers function right, but the driver of the car does not perform correction. Ignores the received information. • The driver of the car does not have enough background information, knowledge: driver of car ”A” is not familiar with the speed limit, or – although this is not very probable in this example – does not know what are the steps of the correction.This example highlights the issues the experts of ergonomics deal with while designing thehuman-machine interface. On Figure 1. the essential elements of the interface aredemonstrated: the display, the controller and the feedback, which are set in the context of thesystem, the environment, the task, the machine and the user. Figure 1.: Encounter of Human and Machine: Interface. In the first part of the chapter the chronological evolution of the human-machineinterface problem will be discussed, from the sensory-motoric fitting to the encounter ofhuman and artificial intelligence. Human-Machine Interface on the Sensory-motoric and Cognitive Level 31
  32. 32. It was during the Second World War that pointed out dramatically the challenges ofthe designing of the human-machine interface (Grudin, 2008). Solutions far from the optimalincreased the possibility of errors, which claimed human and financial losses or lead to thetechnically improved weapon-systems’ disability to reach their planned parameters (Harvey,2004). Comparisons made by Grether (1949) indicated the negative consequences of theignorance of human factors in the process of designing. He observed altimeters that eithertook human factors into consideration or not: instruments that took human factors intoconsideration were faster and more punctual to read. Accordingly the first ergonomiclaboratories were founded in the military (e.g. MANPRINT in the U.S.A.). There are twoimportant issues to be considered for the researchers and practical experts: in what formshould the machine give signals and share information with the user (display), and what typeof operating board should it have (control). The problem of the interface was altered by the widespread of computers, theappearance of the personal computers at the beginning of the1980s. Discovery of the siliconechip and the widespread of computers opened a new chapter in the history of ergonomics:researches on cognitive- and software-ergonomics (Hendrick, 2002). With the help ofpersonal computers the common man had to face artificial intelligence more often, soresearches have shifted from the sensory-motoric level to the cognitive. How to fit the humanand the artificial intelligence? In order to solve this, the first thing to be found out is howhuman information processing, thinking works: what is the human attention, memory like,what characterizes human decision-making, what is the mental pressure a human can bear, orwhat mental pressure is optimal for humans, how can machines handle and benefit fromhuman creativity? (Noyes and co., 2004). It is important to underline though, that these issues – cognitive- and sensory-motoricfitting – exist alongside one another: to this day there are many researches on how the human-machine interface should look like in order for the human to be able to operate the machinessurrounding him effectively on a sensory-motoric level. The Display that Takes Human Factors into Consideration: According to Lehto and Buck (2008) what should be taken into consideration firstlyduring the designing of the display – and the operators of course – is that the human-machinerelation is communication. Humans tell machines what to do and machines tell human what todo or not to do and give feedback of the consequences of human decisions – orders that is.This communication is very important because miscommunication is often behind accidents, 32
  33. 33. injuries. Communication has many characteristics, but maybe one of the most important onesis how much informationarrives to the human fromthe machine that is howefficient the display of themachine is in transmittingthe information24. In thispart we will take a closerlook at what should betaken into account duringthe process of designing. These are of course general guidelines: as the display can be of many kinds, and it canbe used in many situations, the formulating of any practical advice is very difficult (see e.g.Diaper and Schithi, 1995; Ivergard and Hunt, 2009). But general aspects and guidelines aregood when they use the information collected on human functioning, needs and nature. Knowledge on Human Functioning, Needs and Nature If we want to be able to examine humans, we often turn to the analogy of theinformation processing system which in the case of human beings consists of inputs,intermediate processes and outputs. Inputs are the stimuli coming from our surroundingswhich we either react to or ignore. Between perception and procession on a higher level thereis cognition and attention. What happens on a higher level is often simply referred to as“thinking”. This includes such processes as decision making, problem-solving and creativity.All these human cognitive processes are permeated by memory, short term work-memory aswell as long-term memory. At the end of the process there usually is some motoric reaction,action. This model helps to illustrate what types of information should be taken intoconsideration when designing for humans25 (Noyes, Garland and Bruneau, 2004). The modelshows that the characteristics of perception, cognition, attention, “thinking”, memory andmotoric reactions are primarily interesting for researchers of ergonomics. In the next partsome of these aspects will be described.24 Of course in reality it is about how effective the designer of the machine is in designing a display that takes theconsumer into consideration.25 This is what is called “human-centered design” (Harvey, 2004). 33
  34. 34. A very important aspect during the process of designing the display is theunderstanding of the complex nature of human attention. One important characteristic ofhuman attention is that it is selective: humans are able to ignore some information, while theypay attention to others (see e.g. Broadbent, 1958). This is a criterion of normal functioning,for if we have taken in all the information that would lead to overload, so we have todifferentiate between relevant and irrelevant information. This is not an “all or nothing” typeof processing, as some of the information that we do not consciously pay attention to isdetected too. A well-known phenomenon is the cocktail-party effect. On the one hand itdemonstrates that humans are able to pay attention to and follow one particular discussion inthe midst of many other parallel discussions – that is they are able to filter – on the other handif our name is mentioned in a discussion not currently followed, it attracts our attention. Thediscussion rated irrelevant thus is not completely excluded (Moray, 1959). This phenomenonthough shows great individual diversity: in the original experiment of Moray (1959) 33% ofthe observed people heard their names when placed in an irrelevant message, in their moresophisticated observation Wood and Cowan (1995) found this rate to be 34.6%. As it has beenimplied earlier one of the main reasons behind the selectivity of human attention is its limitedcapacity: Kahneman (1973) wrote about attention as a unified, undifferentiated, limitedresource which has to be distributed in accordance to the given tasks. Multiple resourcestheories (e.g. Navon and Gopher, 1979) claim that attention is not unified, but can bedifferentiated in the different channels, but they agree with Kahneman int hat capacity islimited. It further complicates the situation that some researchers (e.g. Schneider and Shiffrin,1977) differentiate between the automatic and the conscious forms of stimulus processing,which indicate different relations to the capacity of attention. Automatic procession is out ofthe individual’s control and is independent from attention. It does not consume resourcesunlike conscious procession, which is controlled and uses resources. In the course of training,education conscious processing can become automatic (an example is the difference betweenthe beginner- and the experienced driver). Some aspects critical from the point of view ofboth the designer and the user are evident even from this short summary, which only indicateswhy it is so important to take the nature of human attention into consideration in the processof the designing of the human-machine interface: • The consumer needs help in deciding what stimuli is relevant and what is irrelevant as the capacity of attention is limited so accordingly it is selective too. The detection of irrelevant stimuli lessens the probability of the detection of the relevant 34
  35. 35. stimuli, while the failing of the detection of the relevant stimuli increases the risk of errors, accidents, human and financial losses. • The nature of attention differs greatly among the individuals. On the one hand this concerns the capacity of attention (see e.g. Just&Carpenter, 1992; Cowan, 2001; Halford, Wilson, &Phillips, 1998), on the other hand it also concerns phenomena like to what extent can the individual follow the channel previously rated irrelevant (Moray, 1959; Wood&Cowan, 1995). • Different processes need different capacity: automatic processing does not use up attention resources, while conscious processing does (Schneider and Shiffrin, 1977). Education and training might turn conscious processing into automatic. • The limited capacity of attention predicts that certain aspects of the environment and the task will lead to errors: for example if the user is asked to divide his attention between two resource-consuming tasks (e.g. he has to read to displays at the same time), or if alongside the relevant stimulus there are too many irrelevant stimuli (e.g. he has to read a display but there are too many discussions going on around him). If these situations are unavoidable, then the possibility of errors should be reduced in the process of the designing or in worse cases at least the consequences of the errors. In the first scenario, when the user is asked to read two displays, we can profit from one of the sensory channels not being filled (e.g. the task is visual and the user can be warned about a problem with a sound). The problem of the capacity of attention goes hand in hand with the problem of howmuch a human can bear. Yerkes and Dodson (1908) demonstrated that between load/activityand performance/efficiency there is an upside-down U-shaped connection (this is the so-calledYerkes-Dodson law). With low activity (underload) efficiency is low too. The increase ofactivity leads to the improvement of efficiency to a certain point (according to the hypothesisthis is because the increase of activity has an energizing effect). After this point the increaseof activity leads to the decrease of efficiency (presumably because of such factors as stress).The connection proposed by Yerkes and Dodson (1908) has been approved in manyresearches (for example Broadhurst, 1959; Duffy, 1962; Anderson, 1988), although as for thereasons of the connection the results are controversial (Anderson, Revelle and Lynch, 1989). 35
  36. 36. What is important from the point of view of designing is the optimal level of theloading: the level where efficiency is thehighest. Interestingly enough it is thewidespread of computerization that ignores thisconnection observed more than a 100 years agothe most. Ivergard and Hunt (2009) claim thatthe appearance of the computer often involvesthe disappearance of the consumer’s active roledisplayed in Fig. 1. Instead the computer entersthe circle of communication and operation between human and machine as shown in Fig. 4. Figure 4: The Computer Entering in Between Consumer and Machine (Ivergard és Hunt, 2009). Ivergard and Hunt (2009) find this to be a problem because with the decrease of theconsumer’s active role his best abilities are taken away (such as flexibility, experience, long-term memory, and so on), highlighting at the same time his weak points (for instance thatmost humans are not very good at maintaining attention in so-called vigilance situationswhere vigilance is important). In the system presented in Fig. 4. humans fill such a positionand role that his abilities do not qualify him for26. In systems using computers theparticipation of humans have to be relied on which is accounted for by the negativeconsequences of underload. Wood (2004) finds that the greatest problem is that most oftoday’s systems require very low or absolutely no input from the operator in 95% of the time,while if something goes wrong the claims on the operator become very high suddenly. Thegoal is the minimalization of the chance of the operator falling out from the controlling cycleeither because he is daydreaming, his attention fades or he collapses under pressure. Wood(2004) enlists a couple of possible solutions: personal factors (e.g. the decreasing of the26 We have to note though that in reality the situation described on Fig. 4. does not exist because computersovertaking all information-gathering and directing functions have not been invented yet. 36
  37. 37. possibility of sleep deprivation by redesigning ill-organized shifts), design of systems (e.g. theintroduction of secondary tasks that would increase, or have the activity stagnate, avoiding sothe monotonization of the system), design of instruments (e.g. the avoiding of hypnotizingeffects by avoiding recurring, monotone audio signals), design of environment (e.g. avoidingthe too quiet, too warm, too calm, too neutral environment), design of instruments (e.g. thedesigning of an interface that requires movement, direct verbal communication andteamwork). Three further aspects during the process of designing: • The human information processing system is essentially set for expectations. Humans are less likely to respond to stimuli that they do not expect, in fact they are more likely to hear and see what they want to hear and see. • The operation of the memory responsible for responding to short-term stimuli suggests that it is a good designing strategy if the information appears on the display when it is needed (so for example not sooner, for instance during a former phase of the process). • It is an important aspect for most humans how much effort do they have to make in order to get the given information: what first appears to be a demanding task many people will avoid. This is especially true if there are more stimuli around trying to claim the human’s attention. So the designer has to design an interface where the information is quickly and easily accessed. In accordance with this and other basic information on humans, some principles canbe identified in connection with the designing of displays. It is essential that the informationon the display is relevant, easily accessible, easily discriminated. It is important that thecriteria, function, danger or ill-use of the task have valid indicators. Before describing theprinciples of designing in detail the boarder line between design and ergonomics has to bemade clear: Norman (1988) differentiates between artistic value and ergonomic usability. One more subject has to be dealt with shortly: the types of displays. Displays arenormally visual or audio (or the combinations of the two). Displays relying on other 37
  38. 38. modalities are rare (e.g. the sense of smell or touch). Visual displays can be static whichmeans that their content does not change: for example signals, labels, road signs, books. Theother type is the dynamic display which represents variable information: such as themilometer, fuel indicator, oil pressure indicator or the display indicating the temperature ofthe cooling water. Dynamic displays can be analogue or digital depending on in what formthey show the information. In most cars for instance dilatometers are analogue though thereare some digital ones too. Displays can be grouped along their function too: 1. status displays:such as the milometer, which represents a current state 2. warning displays: these indicateunusual states, danger, such as the different sirens 3. predictive displays: these makepredictions based on data and trends of the system, for example the system that based on thecar’s average fuel-consumption and the currently available fuel predicts for how many morekilometers will the fuel be sufficient for 4 instruction, recommendation, order displays. Animportant question is how the display encodes the information? There are several options:spatial (for example diagrams, charts, figures, which represent elements connecting throughspace and time); symbolic (for example letters, numbers, or other non-verbal symbols); andimagery (for example the use of the image of fire, flame on a sign indicating danger). The Principles of Designing In the following section two overlapping principle-systems will be discussed. The firstone is by Lehto and Buck (2008) consisting of 27 elements, and the other is by Macredie andCoughlan (2004) consisting of 7 elements. Lehto and Buck (2008): The 27 Principles of Designing These 27 principles can be drawn up by 4 wider topics (Figure 5.): 38
  39. 39. Figure 5: The 4 main topic in display design by Lehto and Buck (2008) First Topic: The Selection of the Sensory Modality First the designer has to decide which sensory modality is most in accordance with theapplication in question. The first designing principle is related to this: • First Principle: the planned function of the display – what it wants to show –, what are the sensory requirements of the background tasks, of what nature are the perception and detection of the future consumer (the senses of seeing and hearing of elderly people are usually worse than that of younger generations) are the factors that determine which sensory modality is the best. This is obviously a complex topic, so we are forced to focus on a few, general realizations: if we want to put a big amount of information on the display, then we do not really have a choice – the display will have to be visual. Some other modality can also be part of the display, but visuality is an obligatory element. When the designer intends to place little information on the display, then the choice among the sensory modalities is not so evident anymore. Audio signals for example are good for drawing attention to change, to unusual, urgent situations. It is not by any chance that these are mostly used as alarm signals. When choosing the modality it is very important to take other factors of the situation, the system into consideration: for example under how much visual pressure does the 39
  40. 40. consumer have to function? If it is a lot then the application of another modality (e.g. the sense of hearing, seeing or smelling) in the display is advisable. A good example is the use of tactile signals (e.g. the vibration of mobile phones), in situations that claim both the visual and the audio channels. Of course all modalities have their advantages and disadvantages: the use of audio channels in noisy environments for example is not very favourable, and loud signals in themselves can puzzle the consumer (a good example is the already described case where the operators of the Three Mile Island nuclear power plant distracted by the too loud, warning sirens, leading to and even greater disaster). • Second Principle: displays combining sensory modalities are especially effective. An example would be the kind of computer screen that gives an audio signal when an important message arrives (this way combining the visual display and the audio signal). This is especially useful when the user has to follow more than one display at a time. This way, if he receives an audio signal when a critical value appears on one of the displays, then it is more likely that he will be able to respond in time to the current situation. Second Topic: The Positioning and Arranging of the Display The second large topic in the designing of the display is the positioning and arrangingof the display. • Third Principle: visual displays have to be placed where they are visible, and the more important information has to be placed into a center position. Displays not detectable for humans are not detected. Important information has to be placed in the center, so that they can be seen more easily, more often, more accurately. During designing possible obstacles have to be taken into consideration such as plants or other signs in the displays’ surroundings. Visual overload is the problem of big cities: too many lights, neon can confuse the consumer (for instance the driving person trying to read the road signs). • Fourth Principle: the display has to show the information when it is needed. This is because of work memory restrictions: if the information is introduced at the right time (and no sooner or later), then it does not have to be remembered and cannot be forgotten. This reduces the chance of making an error a great deal. 40
  41. 41. • Fifth Principle: if there is more than one display then the displays, if there is only one display then the elements of the display have to be arranged according to the sequence, steps of the process. The usefulness of this is easy to see: the sequent arrangement and the not sequent arrangement differ significantly in how much eye movement is required in the performing of the task. If the arrangement is consistent with the sequence then the time spent on searching is reduced, so more time can be spent on working on other parts of the task. • Sixth Principle: in the case of tasks which require the integration of the information the integration has to be presented on the level of the display as well. Elements of the display have to be arranged so that the connections and differences of the elements are easily perceived. Colour-coding is a common strategy, but there are other options too. For example if the related indicators are designed so that they point in the same direction in case of normal functioning, then the different position of an indicator will instantly gives a warning that something is wrong. This way the problem is recognized without the consumer’s close examination. • Seventh Principle: indicators of the displays that are near to one another will probably be perceived as cohesive elements. This is the principle of proximity. If the proximity is actual functional proximity as well, then it can be made even more obvious by placing the cohesive elements into a frame (for example by a light-grey metal frame). • Eighth Principle: the good designer positions the display and the elements of the display so that they have a clear spatial reference. Third Topic: The Visibility of the Display’s Elements Visibility is one of the most emphasized criteria in the designing of displays. The sizeof the displays is obviously important from this point of view, though the recommended sizedepends on many different factors (for instance from how far the display needs to beperceived, how much lighting is there, etc). • Ninth and Tenth Principle: individual differences and circumstances should be taken into account during the process of designing. For example characters and symbols should be larger and bold when visual conditions are poor or readability is important. • Eleventh Principle: the contrast between visual elements and their background should be adequate on a display. For instance in case of printed material the brightness contrast between characters and their background has to be at least 50%. In most cases 41